Adhesive compositions for bonding and filling large assemblies

ABSTRACT

Adhesive composition for bonding and filling large assemblies, including a mixture of about 5 percent to about 75 percent by weight of a thermoplastic polymer, about 0.5 percent to about 35 percent by weight of a polyester resin or vinyl ester resin, and about 20 percent to about 80 percent by weight of an alkyl acrylate or methacrylate monomer.

RELATED U.S. APPLICATION

This application is a divisional application of application Ser. No.10/688,441, filed on Oct. 17, 2003, now abandoned which application is acontinuation-in-part of applications Ser. No. 09/902,436 filed Jul. 10,2001, now U.S. Pat. No. 6,602,958, which issued on Aug. 5, 2003, andSer. No. 10/634,316 filed Aug. 5, 2003, now U.S. Pat. No. 6,852,801,which issued on Feb. 8, 2005.

BACKGROUND OF INVENTION Field of Invention

This invention relates to polymerizable vinyl adhesive or fillingcompositions that are useful for a variety of adhesive, coating,filling, repair and related applications. More particularly, thisinvention relates to two-part room-temperature curing polymerizablevinyl adhesive compositions comprising mixtures of free-radicalpolymerizable monomers and additives that generate heat and undergoexpansion and contraction during the polymerization process. Theimproved compositions comprise mixtures of elastomers, thermoplasticresins, acrylate, methacrylate and styrenic monomers, and polyester orvinyl ester resins that can be applied in large masses or thick crosssections without gassing and void formation from the exothermic curereaction. It also relates to improvements in the ability of adhesivesbased on the compositions to bond thermoplastic and thermoset materials,and to bond such materials with a reduced tendency to cause“read-through” in the bonded area. It further relates to improvements inthe ability of the compositions to cure with a tack-free surface and lowresidual odor, especially when formulated to have a long open workingtime applications involving large parts or assemblies. It still furtherrelates to improvements in the physical properties and adhesive bondingcapabilities of the modified compositions.

Background

Polymerizable vinyl adhesive compositions that are useful for a varietyof adhesive, coating, filling, repair and related applications are wellknown in the art. Prior art compositions include formulations based onacrylate and methacrylate monomers, styrene monomer and styrenederivatives as well as polyester and vinyl ester resins. Thecompositions are generally liquids or pastes that polymerize and curewhen two separately packaged components, one of which contains apolymerization initiator, generally a peroxide, and the other of whichcontains a promoter, generally an amine, are mixed just prior to use.

A particularly useful group of polymerizable vinyl compositionscomprises mixtures of dissolved or dispersed polymers in acrylate ormethacrylate monomers. Such compositions can provide a number ofperformance benefits for adhesive bonding and related applications,including high bond strength, adhesion to a variety of materials withminimal surface preparation, and rapid curing. Methyl methacrylate is apreferred monomer for these adhesives because it is relatively low incost and provides high strength properties in formulated compositions.This group of polymerizable compositions is recognized by those skilledin the art as being superior in many respects to those based onpolyester resins and vinyl ester resins, particularly in terms of theirductility and adhesion to a variety of material surfaces.

Polyester resins generally contain styrene, which is lower in cost thanmethyl methacrylate. They are widely used in automobile body fillers,polyester marine putties, and other filling, bonding and repairmaterials. Polyester/styrene compositions are preferred for applicationsthat emphasize the ability to economically fill large voids and gapswith adequate functional performance rather than those that emphasizephysical properties and related performance attributes at a premiumcost. Thus, one surprising aspect of this invention is the achievementof improvements in the performance of the inventive compositions throughthe incorporation of polyester resins.

Many of the benefits provided by the inventive compositions are usefulfor the non-adhesive applications cited above. However, adhesiveapplications are among the most demanding of those anticipated for suchcompositions. For this reason, the discussion and examples that follow,and the inventive improvements therein will emphasize adhesiveapplications, with the understanding that they can readily be extendedto the other applications cited.

The growing acceptance of methacrylate adhesives has extended their useto larger and larger assemblies and applications, which has resulted inmore demanding application requirements. For example, large fabricatedassemblies require adhesives with longer open time. For adhesiveapplications, open time, working time, and open working time areinterchangeable terms that define the elapsed time between the mixing ofthe separate adhesive components and the attainment of a degree ofpolymerization or cure that prevents effective bond formation. At theend of the open working time, the adhesive either attains a very highviscosity, forms a skin on the surface, or both, preventing effectivewetting for good bond formation. For other applications, this intervalis often referred to as the gel time or pot life for the composition,which is the time after mixing at which it becomes too thick or viscousto continue applying it. Conventional and prior art techniques forincreasing the open working time of adhesives by retarding the onset ofcure or cure rate of the composition with chemical inhibitors orretarders often introduce unwanted negative factors or compromises inthe application or performance characteristics of the compositions.

Another factor in the use of adhesives for bonding large assemblies isthe size of the gaps between the bonded components. As the size of theparts to be bonded increases, so generally does the size of the gapbetween the mating parts. This can be a particular problem with openmolded fiberglass structures, which are prevalent in the construction ofboats, large vehicular assemblies, architectural structures, bridgedecks, and other large structures. When traditional polymerizablemethacrylate adhesives are applied in such thick gaps, the exothermicreaction of curing and the volatility of the monomer generally causegassing and the formation of voids in the adhesive bond which lead tounacceptable bond integrity and part performance. The additivetechniques described above for increasing open working time can also beused to reduce the exotherm and gassing problem, but the same negativeapplication and performance characteristics generally result. Anothertechnique, also discussed below, is the use of inert fillers to reducethis exothermic effect. However, such fillers often have a negativeeffect on the strength and durability of the compositions in adhesiveapplications.

Yet another factor addressed by the inventive compositions, especiallyin the assembly of boats and vehicles, is a phenomenon referred to asread-through or print-through. This is an appearance problem that canresult when an adhesive is used to bond an inner reinforcement,stiffener, bracket or other component to an outer panel or “skin” thathas a smooth or glossy finish. In transportation applications, suchsurfaces are generally referred to as “class A” surfaces. At the end ofthe curing process, or during post-curing processes, certain adhesives,especially those that undergo exothermic polymerization and which changedimensions because of expansion and contraction during the exotherm andcooling associated with the curing process, can contribute to theformation of surface irregularities on the outer or “show” surface ofthe bonded part. The irregularity is generally a depression, outline,distortion or other disturbance of the surface that is visible to theeye and which is aesthetically objectionable. The occurrence andseverity of the problem generally increases with the thickness of thebond and the overall mass of adhesive involved. The causes of suchappearance problems can be complex, including contributions from thespecific nature of the bonded substrates. These include part thickness,the state of cure of thermoset parts when bonded, the thermalconductivity and expansion coefficients of the bonded materials, theproperties of coatings applied on the parts, and other factors.Irrespective of what other factors may be involved in the development ofread-through or print through, it is generally observed that adhesiveswith less tendency to exotherm and undergo dimensional changes duringthe curing process have less tendency to contribute to the phenomenon.

A number of techniques have been used in efforts to overcome thisproblem. These often involve the addition of materials that effectivelyreduce the proportion of reactive monomer in order to reduce itscontribution to dimensional changes, shrinkage and exotherm. Thesematerials include inert liquid plasticizers, which act as diluents, andfillers, which act as extenders and absorb some of the heat ofpolymerization. A related technique involves the use of hollow,expanding microspheres that increase the volume of the curing mass andhelp offset the shrinkage. Yet another technique is the use ofthermoplastic polymers that phase separate during the polymerizationprocess and create internal voids in the material that offset shrinkage.However, as in the case of the gassing problem noted above, theexclusive addition of these inert components in quantities that aresufficient to effectively reduce read through are generally detrimentalto the performance of the adhesives. However, they may be used toadvantage in combination with the improvements of the inventivecompositions.

As previously noted, the usual method of addressing the open workingtime issues and the exothermic gassing problem, both of which arerelated to the rate of the curing reaction, is to reduce the reactivityof the composition by using smaller proportions of polymerizationinitiators, selecting less reactive initiating species, adding retardingadditives or chain transfer agents, or a combination of thesetechniques. However, as pointed out in U.S. Pat. No. 5,859,160referenced below, these techniques can allow other, undesirablecompeting side reactions such as oxygen inhibition to interfere witheffective polymerization and bond formation. The disadvantages of suchair inhibition, as noted in U.S. Pat. No. 5,932,638 also referencedbelow, include weakening of the adhesive bond, increased odor resultingfrom escaping, unreacted monomer, and problems related to tackiness ofthe surface of the adhesive. The problem is especially acute when lowlevels of catalytic species and added retarding agents are used toextend the open working time of methacrylate based adhesive compositionsto periods of about 45 minutes to one hour or more. The problem isfurther exacerbated by low ambient application temperatures that furtherreduce the cure rate, and may prevent completion of the free-radicalcuring process.

Another well-known technique for retarding the cure rate and therebyextending the available time for application of polymerizable vinylcompositions, including methacrylate adhesives, is the addition ofcertain substituted styrene monomers such as a-methyl styrene. When thecomposition is based on methyl methacrylate, styrene as well assubstituted styrenes are effective, as disclosed in U.S. Pat. No.5,656,345.

U.S. Pat. No. 5,859,160 discloses the styrenic monomer technique ingreater detail, but provides no specific references or examples ofadhesive applications or properties, or effects of the added styrenicmonomers on them. It is claimed that the deceleration of the cure rateoccurs without adversely effecting completion of cure and the propertiesof the curable composition after it has cured. The use of the inventionin formulating adhesive compositions is suggested. It is well known tothose skilled in the art that the addition of styrenic monomers tocertain methacrylate compositions, especially when combined with lowlevels of catalytic species to extend open time and reduce exothermicgassing, can have a negative effect on the cure behavior of adhesives.

U.S. Pat. No. 6,291,593 discloses methacrylate adhesive compositionsthat contain a retarding additive to extend the open time and/or reducethe peak exotherm temperature upon curing. Zinc compounds such as zincchloride are preferred.

U.S. Pat. No. 5,932,638 discloses the use of certain para-halogenatedaniline derivatives to overcome the problems associated with poorsurface cure of adhesive compositions resulting from air inhibition.Compositions containing up to about 10 percent by weight of unsaturatedpolyester resin are disclosed. The cited improvement in the surface cureis a reduction in the thickness of the uncured surface layer exposed toair from about 0.025 inch to about 0.002 to about 0.003 inches. However,actual commercial experience has shown that even the lesser amounts ofuncured adhesive cited can be sufficient to cause serious lingering odorproblems. Such problems can occur when, for example, the incompletelycured surface of a squeezed out bead or “fillet” of adhesive is in aconfined area such the stringer grid of a boat. The problem can befurther exacerbated when the fillet or other uncured adhesive bond areais trimmed or smoothed with a spatula or other device that smears a thinfilm of the adhesive against an exposed surface such as the boat hull.The resulting thin film of adhesive is especially susceptible to theeffects of air inhibition. Trapped vapors can eventually migrate to theenclosed cabin area of the boat and create an objectionable orunacceptable level of odor in spite of the very low levels that arepresent. This is because the detectable odor threshold level for methylmethacrylate monomer is about 0.5 parts per million or less.

There is clearly a need for improved adhesive compositions that provideextended open working time, the ability to cure in large, thick masseswithout gassing, to provide fully cured, tack free surfaces with littleor no residual odor resulting from unpolymerized monomer, and to curewith reduced read-through effects on the finished outer surfaces ofboats, vehicles, and other appearance sensitive assemblies whilemaintaining or improving the performance of the cured adhesive.

It has now been discovered that the combination of polyester or vinylester resins and certain acrylate or methacrylate adhesive compositionsprovides these needed improvements. In contrast to the technique ofadding specific retarding additives detailed above, which entail a riskof negative effects on adhesive properties, the addition of polyesterresins can impart multiple benefits which will become apparent in thediscussion that follows.

U.S. Pat. No. 5,932,638 discloses the optional inclusion of from 0 toabout 10 percent by weight of a polyester resin in methacrylatecompositions.

U.S. Pat. No. 5,859,160, also discloses the optional inclusion of from 0to about 10 percent by weight of an unsaturated polyester resin inmethacrylate adhesive compositions.

The '638 Patent and the '160 Patent cite U.S. Pat. Nos. 3,321,351,4,223,115, 4,293,665, and 4,467,071, which disclose the incorporation ofunsaturated polyester resins in methacrylate adhesive compositions. Asin the references cited above, the '115, '665 and '071 Patents disclosethe optional inclusion of from 0 to about 10 percent by weight ofunsaturated polyester resin. Example IV in the each of the '115 and '665Patents, which claims improvements in metal adhesive bond durabilitythrough the addition of phosphate ester materials, includes 3 percent byweight of an unsaturated polyester resin.

In all of the above-cited references, the methacrylate compositioncontains at least about 10 percent, and generally 15-20 percent or moreof a polymeric species to provide toughness in the cured composition.Preferred polymers include polychloroprene, chlorosulfonatedpolyethylene, mixtures of chlorinated polyethylene with sulfonylchlorides, polybutadiene, butadiene copolymers, and polyacrylaterubbers. No particular preference is stated for selection among thesepolymers, whether or not an unsaturated polyester resin is present.

U.S. Pat. No. 3,321,351 discloses compositions containing unsaturatedpolyester resins, vinyl monomers and their polymerizates (specificallymethyl methacrylate and polymers thereof, styrene monomer and polymersthereof), polychloroprene rubber and polyvinyl ethers. The specificationgenerally discloses 10-85% vinyl monomer, 0-50% vinyl polymer, 0-80%unsaturated polyester and 0-40% polyvinyl vinyl ethers. In the examples,however, when methyl methacrylate is included in the compositions, andno neoprene is included, no more than 15 percent polyester resin isincluded. When both methyl methacrylate and neoprene are present, nomore than 1 percent unsaturated polyester is included. In no case doesthe amount of neoprene exceed 3 percent of the composition.

U.S. Pat. No. 4,548,992 discloses methacrylate adhesive compositionscontaining a modified carboxyl containing nitrile rubber and an alkalimetal or amine salt of an unsaturated polyester resin. The carboxylcontaining nitrile rubber is modified by reaction with a methacrylatedphosphate ester. The free carboxyl groups of the polyester resin areneutralized by a metal compound, ammonia or an amine to create amodified polyester resin containing an ionic bond. The ionicbond-containing polyester resin is said to promote adhesion to oilymetal surfaces and to improve the storage stability of the methacrylateadhesive composition.

SUMMARY OF THE INVENTION

The essential feature of this invention is the use of unsaturatedpolyester resins or vinyl ester resins to modify the curing behavior,bonding capabilities and physical properties of polymerizable acrylateor methacrylate compositions. The acrylate or methacrylate compositionsare solutions of thermoplastic or partially thermoplastic polymers orelastomers in acrylate or methacrylate monomers that polymerize whenmixed with a catalyst.

The preferred polyester resins and vinyl ester resins are commercialproducts that are typically supplied as liquids that are catalyzed withperoxides and promoters and used for a variety of applications includinglaminated and cast parts and structural components, coatings, adhesivesand repair materials.

The preferred polymers are synthetic elastomeric and thermoplasticpolymers. The preferred monomers are low molecular weight acrylate andmethacrylate monomers. The most preferred monomer is methylmethacrylate.

This invention provides compositions that include about 5 percent toabout 75 percent of a thermoplastic or partially thermoplastic polymeror elastomer, about 0.5 percent to about 35 percent of an unsaturatedpolyester resin or vinyl ester resin, and about 20 percent to about 80percent of an acrylate or methacrylate monomer. The inventivecompositions exhibit better control of the exothermic curing anddimensional changes associated with adhesives and filling compositions.As a result, they can be applied in thicker masses and can be used tobond and fill large areas and gaps with greatly reduced tendency to gasor boil, exhibit read-through or print-through or other effects ofreaction exotherm, with freedom from the negative effects ofunder-curing at the surface or in thin cross-sections or films.

DETAILED DESCRIPTION OF INVENTION

The polyester and vinyl ester resins utilized in this invention are wellknown to those skilled in the art. The resins and their applications aredescribed in detail in a number of publications, including “Handbook ofComposites”, second edition, S. T. Peters, Editor, published by Chapmanand Hall which is included herein by reference.

Unsaturated polyesters are condensation reaction products of polybasicacids or anhydrides with polyhydric alcohols. After the condensationreaction is completed, the resulting resin, generally a solid orsemisolid, is diluted with an unsaturated monomer to establish thedesired viscosity, reactivity and end use properties.

Preferred unsaturated monomers include styrene, alpha-methylstyrene,2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-t-butylstyrene,3-t-butylstyrene, 4-t-butylstyrene, 1,3-divinylbenzene,1,4-divinylbenzene, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene,and the like, and mixtures comprising at least one of the foregoingalkenyl aromatic monomers. Preferred alkenyl aromatic monomers furtherinclude styrenes having from 1 to 5 halogen substituents on the aromaticring, and mixtures comprising at least one such halogenated styrene. Themonomer mixture may also contain an acrylate or methacrylate monomersuch as methyl methacrylate. The monomer is generally present in anamount of about 30 to about 60 parts per 100 parts resin.

Specific examples of unsaturated polybasic acids that may be used toform the unsaturated polyester resins include maleic acid, fumaric acid,itaconic acid, citraconic acid, chloromaleic acid, nadic acid,tetrahydrophthalic acid, endo-methylenetetrahydrophthalic acid,hexachloro-endo-methylenetetrahydrophthalic acid and other unsaturateddi-and polybasic acids and halogenated acids, as well as theircorresponding esters and anhydrides. Preferred unsaturated acids includemaleic acid and fumaric acid, and their corresponding esters andanhydrides.

Polyfunctional saturated and aromatic acids are employed in conjunctionwith the polybasic unsaturated acids to reduce the density of theethylenic unsaturation and provide desired chemical and mechanicalproperties for specific applications. Examples of saturated and aromaticpolybasic acids include succinic acid, adipic acid, sebacic acid,azelaic acid, dodecanedioic acid, eicoic acid, phthalic acid,isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid(CHDA), and the like, halogenated acids such as tetrabromophthalic acid,as well as their esters and anhydrides. Preferred aromatic polybasicacids include phthalic acid, terephthalic acid and isophthalic acid, andtheir corresponding esters and anhydrides. Polyester resins that employthem are referred to as “orthophthalic” and “isophthalic” or “ortho” and“iso” resins, respectively.

Examples of useful polyhydric alcohols include ethylene glycol,propylene glycol, 1,2-propanediol, 2-methyl-1,3-propanediol, diethyleneglycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol,1,4-butanediol, neopentyl glycol, glycerol, triethylene glycol,pentanediol, hexylene glycol, hydrogenated bisphenol A, bisphenolA-alkylene oxide adducts, tetrabromobisphenol A-alkylene oxide adducts,and the like. Preferred polyhydric alcohols include ethylene glycol,diethylene glycol, propylene glycol, dipropylene glycol, 2-methyl-1,3-propane diol, and neopentyl glycol. Triols, when used are employed invery limited quantity relative to diol to control and limit chainbranching and its effects on molecular weight and viscosity. Preferredtriols include glycerol and trimethylol propane.

More recently, dicyclopentadiene (DCPD) monomer has been used tosynthesize polyester resins that can be incorporated in higherproportions in styrene monomer to produce “low styrene” resins. Suchresins are generally referred to as “DCPD” resins. They are used tolower the styrene emissions from the processes and facilities thatemploy them.

Vinyl ester resins are described in a number of U.S. patents, including3,564,074, 4,151,219, 4,347,343, 4,472,544, 4,483,963, 4,824,919,3,548,030, and 4,197,390 which are incorporated herein by reference.Vinyl ester resins typically comprise a terminally unsaturated vinylester resin, generally derived from a polyepoxide, and at least onecopolymerizable monomer, generally styrene. The terminally unsaturatedvinyl ester resins are prepared by reacting about equivalent proportionsof a polyepoxide, such as a bisphenol A/epichlorohydrin adduct with anunsaturated monocarboxylic acid such as acrylic or methacrylic acid. Theresulting resin has terminal, polymerizable unsaturated groups. Theresins also may include halogenated polyester and vinyl ester resins.

While any of the above-referenced polyester or vinyl ester resins ormixtures thereof may be used to advantage in the inventive compositions,specific combinations of polyester or vinyl ester resins, methacrylatemonomers and polymers can be formulated to provide specific andsignificant performance benefits and improvements over the prior art.For example, any number of the above described polyester or vinyl esterresins may be used to provide compositions with reduced tendency of thecomposition to gas or boil when the adhesive cures. This can be achievedwith either a relatively short or long open working time. When theworking time is relatively short, for example from about 10 to about 30minutes, the adhesive has the unique advantage of providing relativelyfast curing with the ability to fill thick cross sections or voids withreduced exotherm and without gassing or boiling. Fully cured, void-freebonds can be achieved within about 15 to about 60 minutes, respectively,in thicknesses of up to about one and one half inches. Prior artadhesives with similar cure times are prone to gassing and boiling inthicknesses of one-half inch or less.

When the open time is long, for example, from about 45 to about 90minutes, the adhesive has the ability to cure with a hard, tack-freesurface, as well as the unique ability to cure in thin cross sections orin a thin film, without weak bonds from cure retardation and lingeringodor resulting from unreacted, air-inhibited monomer. In addition,void-free bonds can be obtained within about 90 minutes to about threehours in thicknesses up to three inches. Prior art adhesives with longopen time generally do not cure well in thin cross sections or in thinfilms, and tend to gas and boil in thicknesses greater than about oneinch.

In contrast with the aforementioned technique of employing styrenemonomer or substituted styrene monomers alone as a separate additives,the polyester resins provide multiple benefits without negativelyimpacting the cure of the composition, and in fact even improve thefinal state of cure of the compositions. Other benefits can includeimproved adhesion and physical properties such as tensile strength andtensile elongation.

The choice of resin can influence application, curing and performancecharacteristics to varying degrees depending upon the specificformulation involved. For example, with other variables constant,compositions containing orthophthalic and isophthalic resins generallyachieve a better final state of cure than those containing DCPD resinswhen benzoyl peroxide is used as the catalyst. However, DCPD resinsprovide compositions with significantly less exotherm and shrinkage ordimensional change than orthophthalic or isophthalic resins. In order toadvance the state of cure when a DCPD resin is selected, particularattention must be paid to the selection of peroxide and promoter levels,and the selection of the inhibitor package.

Compositions containing vinyl ester resins or halogenated vinyl esterresins or mixtures thereof tend to exhibit greater exotherm anddimensional change than those containing polyester resins, but theircure speed, ultimate state of cure and heat resistance, defined as theproportion of room temperature strength retained at high temperatures,are superior. If exotherm and dimensional change is not an issue, verystrong, fast-curing bonds with low tendency to gas and boil can beobtained with vinyl ester resins.

The resin employed may be either promoted or unpromoted. Many commercialpolyester and vinyl ester resins contain amines and/or organometalliccompounds as well as inhibitors that are added by the manufacturer toimpart a desired level of reactivity when a peroxide initiator is addedjust prior to use. Such resins are called promoted or pre-promotedresins. Because the resins employed in this invention are additives inreactive methacrylate compositions that have specific catalyticrequirements, it may be preferable in some cases that the polyester andvinyl ester resins contain no catalytic species. The inventive modifiedmethacrylate compositions utilizing such non-promoted resins can then beformulated with the desired level of preferred catalytic species for thedesired application characteristics.

The unsaturated polyester and vinyl ester resins of this invention arecommercially available from a number of U.S. and global suppliers. U.S.suppliers include Alpha Owens Corning (AOC), Ashland Chemical, CookComposites (CCP), Eastman Chemical, Interplastic Corporation, andReichhold. Vinyl ester resins are available from AOC, Ashland, Eastman,Interplastic, Reichhold and Dow Chemical. Global suppliers includeDianippon Chemical in Asia and DSM in Europe. The resins are sold undera number of brand names in various markets. The following is a summaryof the resins and their brand names from the various domestic suppliers:

SUPPLIER RESIN TYPE TRADE NAMES Alpha Owens Ortho PE, DCPD Altek ® H300,H500, H800 Corning Isophthalic PE Pultru, Vipel Terephthalic PE Pultru,Vipel Vinyl Ester Hydropel, Vipel Ashland PE, DCPD, VE AME, Aropol,Hetron Dow Vinyl Ester Derakane Eastman Ortho/Iso/Tere PE Verimac DCPDVinyl Ester Interplastic PE, Vinyl Ester CoREZYN ReichholdOrtho/Iso/Tere/ DION, Polylite DCPD Polyester Vinyl Ester Hydrex, Atlac,DION PE = Polyester, VE = Vinyl Ester

Preferred unsaturated polyester resins of this invention are unsaturatedorthophthalic, isophthalic, terephthalic, DCPD halogenated polyesterresins and mixtures thereof. Preferred orthophthalic and DCPD resinsinclude the Altek 500 and 800 series from AOC, the Polylite 31000,32000, 33000 and 44000 series from Reichhold, and similar resins fromother manufacturers. Preferred isophthalic resins include Vipel F737from AOC and similar resins sold under the trade names DION, ATLAC andPolylite from Reichhold. Preferred DCPD resins include the Altek H800series from AOC and Polylite 44383, 44006 and 44285 from Reichhold.

Resin manufacturers generally produce unpromoted “base” versions of theabove polyester resin types and vinyl ester resins that are blended withother resins to obtain a desired set of properties. Within a givenfamily of resins, grades with varying reactivity and flexibilitycharacteristics are made at high solids levels, generally up to about 70percent.

Most preferred orthophthalic resins are unpromoted, flexibilized, low-tomedium reeactivity versions such as Polylite 31008 from Reichhold andVerimac 711-1530 from Eastman. Most preferred isophthalic andterephthalic resins are unpromoted, flexibilized low to mediumreactivity versions such as AOC T750-70, Polylite 31830 from Reichholdand Verimac 126-0863 from Eastman. Most preferred DCPD resins areunpromoted base resins such as COREZYN 61AA340 from Interplastics andPolylite 44-006 from Reichhold.

Preferred vinyl ester resins, halogenated vinyl ester resins or mixturesthereof include Derakane 411-350 from Dow, Hetron 922 from Ashland,COREZYN VE8300 from Interplastic, DION and Atlac 9100 from Reichhold andVerimac 785-8430 from Eastman. Most preferred vinyl ester resins includeDerakane 411-350 from Dow and DION/Atlac 9100 from Reichhold.

The vinyl ester or polyester resins can be used individually or incombinations to achieve the optimum effects in terms of curing behaviorand physical properties of the cured composition. Virtually anycombination of unsaturated polyester resin and methacrylate adhesivecomposition may be used, but in order to retain the beneficialproperties of the methacrylate adhesive composition, the methacrylateportion should comprise at least about 20 percent of the overallmixture. The compositions of the invention preferably encompass acombination of about 0.5 percent to about 35 percent, preferably fromabout 1 percent to about 25 percent, and most preferably from about 2percent to about 20 percent of an unsaturated polyester resin, a vinylester resin, or a combination thereof.

The preferred polymers of this invention are thermoplastic or partiallythermoplastic polymers and elastomers and may be selected from athermoplastic or partially thermoplastic polymer or elastomer or a blendof two or more thermoplastic or partially thermoplastic polymers, ablend of two or more elastomers, and a blend of one or more elastomerswith one or more thermoplastic or partially thermoplastic polymers. Asused here, the term partially thermoplastic refers to polymers,elastomers, or elastomer-containing polymers that have some degree ofcrosslinking in their structure. One example of such a polymer is acore-shell impact modifier wherein the core, which is typically abutadiene based or acrylic based rubber, is crosslinked to some degreeto provide the desired impact modifying properties or other specificproperties. Another example is Neoprene AG, a polychloroprene elastomersold by duPont Dow Elastomers. In this case, the polychlorprene, whichis normally thermoplastic and soluble, is specifically modified with anagent that imparts light crosslinking to provide unique, gel-likeproperties that beneficially modify the rheology of solutions or rubbercompounds that contain it. Additional examples include elastomericpolymers that are crosslinked to modify them for use as impact modifiersor other property modifiers in formulated rubber, plastic or other resincompositions. Specific examples include Chemigum, a crosslinkedbutadiene acrylonitrile elastomer, and Sunigum, a crosslinked acrylateterpolymer, both sold by Eliokem. In all cases, the crosslinking that isincluded to modify the properties of the polymers renders them insolubleor only partially soluble in the monomers of this invention, whereasfully thermoplastic polymers and elastomers are fully or substantiallysoluble in the monomers.

Preferred thermoplastic, partially thermoplastic, and substantiallysoluble polymers and elastomers and mixtures thereof include, but arenot limited to, diene based polymers including those based on butadieneor isoprene, such as copolymers and multipolymers containingacrylonitrile, styrenic and acrylic monomers; thermoplastic blockcopolymers, multipolymers and impact modifiers based on butadiene,isoprene, ethylene-propylene and ethylene-butylene in combination withstyrene, acrylonitrile and acrylic monomers; acrylonitrile butadienestyrene (ABS) resins and impact modifiers, methacrylate butadienestyrene (MBS) and MABS impact modifiers and polymers, chlorinatedpolymers such as polychloroprenes, chlorinated polyolefins andcopolymers, chlorosulfonated polyethylenes, polyolefins, and copolymersthereof, polyepichlorohydrins and copolymers, vinyl chloride containingpolymers and acrylic based elastomers and impact modifiers. Thepreferred polymers are those which impart toughness and elasticproperties and improve adhesion of the compositions to bondedsubstrates. Other polymers that improve adhesion or other properties butdo not impart toughness may be used to advantage in the inventivecompositions. Examples include polymers, copolymers and multi polymersof styrene, acrylonitile, vinyl chloride and acrylic monomers. Lowmolecular weight, liquid reactive and unreactive elastomers andoligomers may also be used to advantage in the compositions of thisinvention. Examples include liquid vinyl reactive butadiene polymers andcopolymers with acrylonitrile and acrylate monomers sold by Noveon andRicon resins, and any number of other reactive liquid polymers andoligomers sold commercially by Sartomer, Radcure and others.

Most preferred elastomers and polymers include polychloroprenes such asNeoprene AD-5, AD-10 and AG, chlorinated polyethylenes such as Tyrin3611, 3615 and 4211, and chlorosulfonated polyethylenes such as Hypalon20, 30, 40 and 48 sold by duPont Dow elastomers, nitrile elastomers suchas Nipol 401LL, 1201, DN-4555, and 1401LG, sold by Zeon Chemical,crosslinked nitrile elastomers such as Zealloy 1422 sold by Zeon andChemigum P-83 sold by Eliokem, liquid nitrile elastomers such as Hycar1300×33 sold by Noveon, styrene-butadiene-styrene (SBS),styrene-isoprene-styrene (SIS), styrene-ethylene-propylene (SEP) andstyrene-ethylene-butadiene-styrene (SEBS) Block copolymers sold byKraton Polymers, acrylic elastomers such as Hytemp 4051 and 4054 sold byZeon, ethylene-acrylic elastomers such as Vamac D and G sold by duPont,core-shell impact modifiers such as Paraloid BTA 753 (MBS) sold by Rohmand Haas, Blendex 338 (ABS) sold by GE Plastics, FM-10 (all acrylic)sold by Kaneka, and ethylene-propylene based impact modifiers, such asRoyaltuf 372P20 sold by Crompton Chemical.

Preferred monomers are lower molecular weight C₁-C₆ acrylate andmethacrylate monomers. More preferred monomers include methylmethacrylate, ethyl methacrylate, hydroxyethyl methacrylate, propylmethacrylate, hydroxypropyl methacrylate, butyl methacrylate, cyclohexylmethacrylate, methyl acrylate, ethyl acrylate, hydroxyethyl acrylate,propyl acrylate, hydroxypropyl acrylate, butyl acrylate, hexylacrylate,cyclohexyl methacrylate and mixtures thereof. Even more preferredmonomers are methyl methacrylate and ethyl methacrylate. The mostpreferred monomer is methyl methacrylate. Other higher molecular weightmonofunctional or polyfunctional acrylate monomers and oligomers may beused in quantities of up to about 25 percent of the composition in orderto crosslink the cured compositions or impart certain desirableapplication and performance characteristics such as reduced odor,improved wetting and adhesion properties for particular substrates,reduced tendency to solvate sensitive plastic surfaces, includingincompletely cured polyester resin surfaces, and improved flexibility orother mechanical properties.

A more complete understanding of the specific benefits provided by thevarious acrylate and methacrylate compositions and polyester and vinylester resins will be evident from the examples that follow.

The compositions of this invention encompass a combination of about 5percent to about 75 percent, preferably about 7 percent to about 60percent, and most preferably about 10 percent to about 50 percent of athermoplastic or partially thermoplastic polymer or elastomer, about 0.5percent to about 35 percent, preferably about 1 percent to about 25percent, and most preferably about 2 percent to about 20 percent of anunsaturated polyester resin or a vinyl ester resin, and about 20 percentto about 80 percent of at least one acrylate or methacrylate monomer,preferably from about 30 to about 80 percent, and most preferably fromabout 40 to about 70 percent.

Preferred compositions of this invention encompass a combination ofabout 5 percent to about 75 percent, preferably about 7 percent to about60 percent, and most preferably about 10 percent to about 50 percent ofa blend of at least two polymers, about 0.5 percent to about 35 percent,preferably about 1 percent to about 30 percent, and most preferablyabout 2 percent to about 20 percent of an unsaturated polyester resin ora vinyl ester resin, and about 20 percent to about 80 percent of atleast one acrylate or methacrylate monomer, preferably from about 30 toabout 80 percent, and most preferably from about 40 to about 70 percent.

More preferred compositions encompass a combination of about 5 to about75 percent, preferably from about 7 percent to about 60 percent, mostpreferably from about 10 percent to about 50 percent by weight of ablend of at least two elastomeric polymers, or at least one elastomericpolymer and at least one thermoplastic polymer, about 0.5 percent toabout 35 percent, preferably about 1 percent to about 25 percent, andmost preferably about 2 percent to about 20 percent of an unsaturatedpolyester resin or a vinyl ester resin, and about 20 percent to about 80percent of at least one acrylate or methacrylate or monomer, preferablyfrom about 30 to about 80 percent, and most preferably from about 40 toabout 70 percent.

In a further preferred embodiment, the compositions of the inventionencompass a combination of about 5 to about 75 percent, preferably fromabout 7 percent to about 60 percent, most preferably from about 10percent to about 50 percent by weight of a blend of at least oneelastomer and at least one elastomer modified thermoplastic polymer oran elastomer-containing core-shell impact modifier, about 0.5 percent toabout 35 percent, preferably about 1 percent to about 25 percent, andmost preferably about 2 percent to about 20 percent of an unsaturatedpolyester resin or a vinyl ester resin, and about 20 percent to about 80percent of at least one methacrylate monomer, preferably from about 30to about 80 percent, and most preferably from about 40 to about 70percent.

In a most preferred embodiment, the compositions of the inventionencompass a combination of about 5 to about 75 percent, preferably fromabout 7 percent to about 60 percent, most preferably from about 10percent to about 50 percent by weight of a blend of polymers thatincludes at least one chlorinated polymer and at least one nitrileelastomer or thermoplastic acrylonitrile polymer as disclosed in U.S.Pat. No. 6,602,958, about 0.5 percent to about 35 percent, preferablyabout 1 percent to about 25 percent, and most preferably about 2 percentto about 20 percent of an unsaturated polyester resin or a vinyl esterresin, and about 20 percent to about 80 percent of at least onemethacrylate monomer, preferably from about 30 to about 80 percent, andmost preferably from about 40 to about 70 percent.

In order to promote adhesion to various substrates, including metallicsubstrates, the compositions may also contain from 0.01 to about 20percent, preferably from 0.1 to about 15 percent of a polymerizableorganic acid monomer or oligomer. These include vinyl reactivecarboxylic acid monomers that are well known to those skilled in theart. Preferred polymerizable carboxylic acid monomers are acrylic acid,methacrylic acid, maleic acid, fumaric acid and itaconic acid. Otherpreferred polymerizable acid monomers or oligomers inlude the vinylfunctional derivatives of phosphoric acid disclosed in U.S. Pat. No.4,223,115 and 4,293,665 cited earlier. Specific preferred examples arethe mixed mono- and di- substituted phosphate esters derived fromhydroxyethyl methacrylate, sold under the tradename Light Ester P-1 Mand P-2M by Kyoeisha Chemical Co., LTD, Japan.

The selection of the acid monomer or oligomer or mixture thereof dependson the anticipated substrate bonding requirements and other effectsimparted by the polymerizable acid employed. For example, methacrylicacid is preferred in many instances because it increases the cure speedof the adhesive composition and improves adhesion to mild steel. Thepartially substituted phosphated esters are preferred when improvedadhesion and durability are required on unprepared aluminum andstainless steel substrates. However, the acid functional phosphateesters can retard the cure speed of certain formulations. Maleic acid isshown in U.S. Pat. No. 4,714,730 to enhance adhesion to difficult tobond substrates such as nylon. In some cases, mixtures of acidicmonomers and oligomers can be used to advantage when adhesion to avariety of substrates is required. The precise selection and effects ofthe mixed acids is influenced by the other components in the formulationand the acceptable perfomance compromises for a given application.

Various viscosity control agents such as organoclays, fumed silica orthe like may be added in amounts ranging from about 0.1 to about 10percent based on the system weight to control the viscosity of theadhesive. Additional fillers may be added in significantly largeramounts to reduce the cost of the adhesive or to modify certain physicalproperties. In this case, quantity of the filler or extender would beconsidered separately as an additive to the base polymer and monomercomposition as described above. Common particulate fillers or extenderssuch as clay, talc, calcium carbonate, silica and alumina trihydrate canbe added in amounts up to about 50 percent or more of the composition byweight in order to achieve specific economic, application or bondingcharacteristics. Inorganic or organic microspheres or microballoons maybe used to reduce the density and cost of the adhesives, as well as toimprove their sanding or finishing characteristics when used as repairmaterials such as automobile body repair products.

Any number of available and well-known catalyst combinations may bechosen to cause the polymerization and curing of the compositions of theinstant invention. Some of the terms used to describe the variouscomponents of the curing system (catalysts, initiators, reducing agents,activators, promoters) are often used interchangeably, and thus theterminology used below may differ from other descriptions used in theart. The primary catalytic species for initiating the polymerization ofthe vinyl monomers of this invention are peroxide or hydroperoxideinitiators. Examples are benzoyl peroxide, cumene hydroperoxide,tertiary butyl hydroperoxide, dicumyl peroxide, tertiary butylperoxyacetate, tertiary butyl perbenzoate, and the like. The peroxideinitiators are used in amounts ranging from about 0.01 to about 10weight percent based on the weight of the adhesive composition.Preferably, the initiators will be used in the amount of about 0.05 toabout 5 weight percent.

In order to prevent premature polymerization of methacrylate adhesivecompositions, including the inventive compositions, one or more freeradical inhibitors or antioxidant stabilizers may be required in theformulation. The selection and use of such additives is well known tothose skilled in the art. The methacrylate monomers used in thecompositions contain inhibitors, generally phenolic compounds, that areadded to the monomers to stabilize them during storage. Many of thepolymers used in the formulations contain heat stabilizers that protectthe polymers during processing and storage. The polyester resins of theinventive compositions also may contain inhibitors. The most commoninhibitors and stabilizers are phenols, quinones and their derivatives,and many can be used interchangeably in the raw materials cited. In somecases, the inhibitors present in these raw materials are sufficient tostabilize the formulated adhesives, and in some cases additionalmaterials may need to be added to assure stability. Because of thevariety of raw materials (with in situ inhibitors) that may be chosen,and the variety of catalyst systems that may be selected to prepare acomposition, the selection of the complete inhibitor package isgenerally the final step in the formulating process. The selection isspecific to each formulation, beyond the scope of this invention, andgenerally proprietary to those skilled in the art.

In addition to the free-radical inhibitors or stabilizers, a chelatingagent may be used to further stabilize the methacrylate compositions.Chelating agents are used as scavengers for trace metal impurities thatcan destabilize the reactive methacrylate formulations. The use andfunction of these additives are disclosed in U.S. Pat. No. 4,038,475 and4,374,940.

A reducing agent is used to induce the room temperature decomposition ofthe peroxide or hydroperoxide initiator at ambient or room temperature.The most common reducing agents for this purpose are well known to thoseskilled in the art and include tertiary aromatic amines andaldehyde-amine reaction products. Useful tertiary amines includeN,N-dimethylaniline, N,N-dimethyl-p-toluidine, N,N-diethyltoluidine,N,N-bis(2-hydroxyethyl) toluidine and other similar aromatic amines usedfor this purpose which are well known in the art. Aldehyde-aminereaction products include such compositions as butyraldehyde-aniline andbutyraldehyde-butylamine derivatives whose active ingredient is adihydropyridine (DHP) formed from condensation of three moles ofaldehyde with one mole of amine. More recently, DHP-enriched versions ofthese compositions have been made available. One such material isReillcat ASY-2, available from Reilly Industries, Inc. This catalyst orinitiator system is most often used in combination with a sulfonylchloride compound and a hydroperoxide as described in U.S. Pat. No.3,890,407 and 4,182,644. The reducing agents are employed in amounts ofup to about 15 weight percent based on the weight of the adhesive.Preferred amounts are 0.01 to about 5 percent.

Transition metal salts, including organometallic compounds such ascobalt, nickel, manganese or iron naphthenate, copper octoate, copperacetylacetonate, iron hexoate, or iron propionate, and other well-knownmetallic compounds act as promoters for the inventive polymerizablecompositions. Promoters, whose effect varies greatly from system tosystem are used in amounts up to about 1-2 weight percent, preferablyabout 1 part per million to about 0.5 weight percent. Most preferredamounts range from about 5 parts per million to about 0.5 percent byweight. Metallic promoters may be used with certain peroxide initiatorsas the primary initiating species or in combination with tertiary amineor amine-aldehyde reducing agents to enhance the rate of polymerization.

The most preferred free radical initiation systems comprise (1) atertiary amine reacting with benzoyl peroxide or another peroxide, (2) aDHP derivative in combination with a sulfonyl chloride compound and ahydroperoxide or another peroxide or (3) an organometallic compound suchas cobalt naphthenate in combination with a hydroperoxide, all threecombinations being capable of inducing the free-radical curing processat room temperature. Combinations of amine or amine aldehyde andmetallic species may be used to advantage in any of the above systems.The precise selection and partitioning of the initiating and inhibitingcomponents for a given composition depend on its specific intendedapplication, subject to the formulating principles well known to thoseskilled in the art.

The adhesive compositions of the invention are characterized by theirability to polymerize in large masses or thick cross sections withoutforming voids, and their ability to cure with a tack-free surface or inthin films with low residual odor, especially when formulated to have along open working time applications involving large parts or assemblies.The compositions are also capable of curing in thick bonds or relativelylarge masses without exhibiting objectionable read-through orprint-through on exposed cosmetic surfaces. They further exhibitimproved physical properties and adhesive bonding capabilities. Suchimprovements include the attainment of higher tensile strength withoutsacrificing tensile elongation, and the capability to bond a variety ofcomposite materials, including certain difficult to bond composites withor without preparation of the surface prior to bonding, as well as avariety of other materials alone or in combination.

The compositions of this invention have been developed primarily toimprove the properties of adhesives. However, the improvements therebydiscovered make these products more useful than previous products oftheir class for repair materials, coatings, bulk casting and any numberof other applications beyond adhesives.

EXAMPLES

MATERIALS AND COMPONENTS UTILIZED IN EXAMPLES Trade name or DescriptionSource Designation or Function or Supplier Neoprene Polychloropreneelastomer DuPont Dow Elastomers Nipol ® Nitrile elastomer Zeon ChemicalsMMA Methyl methacrylate monomer Lucite PARALOID ® MBS impact modifierRohm & Haas Co. BTA 753 MAA Methacrylic acid monomer Lucite DMPTN,N-Dimethyl-p-toluidine First Chemical HET Hydroxyethyl toluidine BayerAG 55% BPO Paste Benzoyl peroxide (55%) in Elf Atochem proprietaryplasticizer mixture Akzo Nobel Derakane ® Vinyl ester (VE) resin DowChemical Vamac ® Ethylene acrylic elastomer duPont LMA Laurylmethacrylate monomer Sartomer Tyrin ® Chlorinated polyethylene DuPontDow Elastomers Hycar ® Reactive liquid BD/AN polymer Noveon, Inc.Kraton ® Styrene/butadiene block Kraton Polymers copolymer HyTemp ®Polyacrylate elastomer Zeon Chemicals Hypalon ® Chlorosulfonatedpolyethylene DuPont Dow Elastomers NOVA NAS-30 Styrene acrylic copolymerNOVA Chemicals Chemigum ® Crosslinked nitrile rubber Eliochem Hycar ®Liquid nitrile polymer Noveon Reillcat ™ Dihydropyridine derivativeReilly Industries, ASY-2 Inc. Luperox ® Cumene hydroperoxide (CHP) ElfAtochem CU 90 MEKP Methyl ethyl ketone peroxide Norac EDTA Solution 5%solutiion of tetrasodium Aldrich ethylenediamine tetraacetate(Na₄EDTA•H₂O) hydrate in 50% aqueous ethanol Light Ester Mixedmethacryloyloxyethyl Kyoeisha Chemical phosphate ester Co. HP 1310Acrylic oligomer Hehr International Polymers

Preparation of Adhesive Compositions

Unless otherwise indicated, the following procedure was used, employingtechniques well known in the art, to prepare the experimental adhesives:

Readily soluble or dispersible elastomers and resins were dissolved inmethyl methacrylate (MMA) monomer in a jar or metal can on a laboratoryroll mill to form stock solutions. The proportions of polymer andmonomer were selected to provide a convenient working viscosity to allowthe addition and blending of successive formulation ingredients. Typicalsolution concentrations in MMA of 15-35 percent by weight of polymerwere selected to provide final solution viscosities ranging from about50,000 to 500,000 cps. It is generally preferable to prepare the stocksolutions in the higher concentration and viscosity range in order to beable to make final viscosity adjustments by diluting the finishedadhesive with MMA monomer. The polymer and monomer were rolled until allof the polymer was dissolved and no lumps or particles of undissolvedmaterial were present.

Experimental adhesives were prepared in plastic beakers in quantitiesranging from about 100-600 grams of finished adhesive. Sufficient stocksolution or a mixture of stock solutions was added to the beaker in thequantity required to provide the desired proportion of elastomer in thefinished adhesive.

When powdered impact modifiers were added to the formulations, they wereadded to the polymer in monomer solution along with any othernon-catalytic liquid ingredients and mixed with a high shear laboratorymixer until a uniform, sometimes grainy paste consistency was achieved.The impact modifiers do not dissolve in the mixture, but rather swell togive the adhesive a gel-like consistency. Generally, two to four hoursis required for the impact modifier to swell and soften sufficiently tobe fully dispersed in the mixture. At this time, the adhesive is mixed asecond time under high shear to form a smooth paste. At the end of thesecond mix, the remaining ingredients are added and thoroughly mixedinto the adhesive. Adhesives formulated with no impact modifier wereprepared by adding the remaining ingredients directly to the mixture ofstock elastomer solutions and thoroughly mixing to form the finishedadhesive.

Final viscosity adjustments were made by adding with MMA monomer toreduce viscosity, or fumed silica or additional impact modifier toincrease viscosity, as required.

Adhesive Evaluation Tests And Methods

Measurement of Exotherm Time and Temperature

The peroxide-and amine-containing adhesive components were mixed in theproportions specified in each example. The mixed sample was degassed ina vacuum desiccator to remove entrapped air and placed in a draft-free,clear plastic temperature regulated test chamber maintained at 75° F.+/−1° F. A thermocouple wire attached to an exotherm recorder wasinserted into the center of the mass of adhesive to record the peaktemperature attained and the time to reach peak temperature.

Cure Characteristics of Molded Thick Castings

In order to simulate thick bond cure characteristics, test molds wereprepared from adhesively bonded 0.25 inch thick polypropylene sheet toprovide a rectangular cavity to form a test casting with dimensions of 8inches (length) by 2 inches (width) by 1.5 inch (height). A mass ofadhesive (approximately 500-600 grams, depending on specific gravity)was mixed and degassed as noted above and transferred to the test moldusing a spatula to pack the mold and smooth the top exposed surface evenwith the top of the mold. The adhesive mass was allowed to cure, and theappearance and condition of the cured casting was observed and recorded.

The presence or absence of voids resulting from gassing or boiling wasnoted. An arbitrary scale of 1 to 4 was used to rank the formulations,with value of 1 representing essentially no gassing or “boiling” withinthe casting or at the surface, and 4 representing excessive “boiling” ofthe mass and gaseous expansion of the mass and formation of surfacevoids. The intermediate values represent increasing degrees of internaland surface void formation during cure.

In order to assess the effectiveness of curing, the hardness of thecasting surface and center (measured in the center of a vertical cutthrough the midpoint of the bead) was measured using a Shore Ddurometer.

Adhesive Bond Strength

Adhesive bonds with open molded fiberglass reinforced polyester testcoupons were prepared, tested and the results reported according to ASTMmethod D5868. The bonds were shimmed to provide a nominal thickness of0.125 inch. Metal bonds were tested according to ASTM D1002 using a bondthickness of 0.010 inch.

When reporting lap shear bond strength results, the followingabbreviations are used throughout the examples for the correspondingfailure modes:

-   AF: ADHESIVE FAILURE. The adhesive cleanly separates from the    substrate surface.-   CF: COHESIVE FAILURE. Failure occurs in the adhesive layer, leaving    a distinct layer of adhesive on each substrate surface.-   TLCF: THIN LAYER COHESIVE FAILURE. The failure appears to be    adhesive in nature, with the bulk of the adhesive on one surface and    a thin residue of adhesive on the other.-   FT or DL: FIBER TEARING OR DELAMINATION of composite substrates.-   SF: Fracture failure and separation of the composite substrate at    the adhesive bondline, with no bond separation.    TENSILE PROPERTIES OF THE BULK ADHESIVES

Bulk stress-strain properties of the adhesives were measured accordingto ASTM test method D638. Test specimens were prepared by mixing asufficient quantity of adhesive to prepare a uniformly flat film ofadhesive approximately 6 to 7 inches in diameter and approximately0.0625 inches thick. The adhesive components were combined in thespecified ratios by simple hand mixing in a beaker. After the adhesivewas thoroughly mixed, the beaker was placed in a vacuum chamber andvacuum was applied intermittently to remove air until the last one ortwo applications of vacuum did not produce additional frothing orexpansion. The adhesive was then transferred to one of two glass orplastic plates approximately 12 inches in diameter with a similar sizedlayer of Mylar release film on top of it. The adhesive was placed in thecenter of the film, and a mating Mylar film and plate were placed overthe adhesive and pressed down uniformly to spread the film. Metal shimswere placed around the perimeter of the plates to establish the desiredfilm thickness.

After the films were cured, the plates were removed. Test dumbbells werecut from the films as specified in the test method, taking care to cutthe specimens from the most void-free section of the film. The filmswere allowed to cure overnight at ambient temperature followed by athermal postcure at 82° C. for one hour prior to cutting the dumbbells.Each test number is the average of five individual test specimens.

EXAMPLES 1-2

Examples 1 and 2 are comparative examples for inventive examples 3-7 and8-12, respectively. They illustrate that when the respective inventiveexamples are formulated without the addition of a vinyl ester resin,they undergo significant gassing and boiling, even though theyeffectively bond open molded FRP composite in normally thin bonded(0.125 inch) cross sections.

TABLE 1 EXAMPLE 1 2 MMA Monomer 68.60 65.60 Neoprene AD-10 20.00 — NipolDN 4555 — 10.00 BTA 753 — 18.00 Lauryl 5.00 5.00 Methacrylate HET 0.400.40 Methacrylic Acid 1.00 1.00 Dibutyl Phthalate 2.00 — Dow Derakane —— Vinyl Ester Resin Fumed Silica 3.00 3.00 55% BPO Paste 1.80 1.80RESULTS Peak Exotherm 39-Gram Mass Time to peak, min. 30.3 44.4Temperature, ° F. 288 275 Thick Cast Bead Cure Observations 8 in × 2 in× 1.5 in Qualitative Cure Rank (1 = Best, 4 = Worst) Surface BoilExcessive Yes Surface Boil Rank 4 3 Hardness, Shore D not tested 30-35(porous) Center of Bead n.t. 50-55 (porous) Lap Shear Strength, PSI OpenMolded FRP n.t. 569 Failure Mode n.t. 100% FT

EXAMPLES 3-7

Examples 3-7 illustrate the effectiveness of a preferred vinyl esterresin in improving the curing performance of methacrylate formulationscontaining a range of elastomeric polymers. Unlike the ComparativeExample 1, the inventive compositions do not boil or gas to causeexpansion and undesirable voids in the thick cast bead that simulates athick bonded cross section.

TABLE 2 EXAMPLE 3 4 5 6 7 MMA Monomer 58.60 58.60 58.60 58.60 58.60Nipol DN 4555 20.00 — — — — Vamac D — 20.00 — — — Kraton D 1102 — —20.00 — — Neoprene AD-10 — — — 20.00 — Tyrin 3615P — — — — 12.00 BTA 753— — — — 8.00 Lauryl 5.00 5.00 5.00 5.00 5.00 Methacrylate HET 0.40 0.400.40 0.40 0.40 MAA 1.00 1.00 1.00 1.00 1.00 DBP 2.00 2.00 2.00 2.00 2.00Dow Derakane 10.00 10.00 10.00 10.00 10.00 VE Resin 411-350 Fumed Silica3.00 3.00 3.00 3.00 3.00 55% BPO Paste 1.80 1.80 1.80 1.80 1.80 RESULTSPeak Exotherm 39 Gram Mass Min. to peak 62.5 9.5 24.2 23.5 24.8Temperature, ° F. 253 303 319 317 304 Thick Cast Bead Cure Observations8 in × 2 in × 1.5 in Qualitative Cure Rank (1 = Best, 4 = Worst) SurfaceBoil None None None None None Surface Boil Rank 4 1 1 1 1 Hardness,Shore D 10-15 60-70 60-65 50-55 45-50 Center of Bead 25-30 65-77 70-7565-70 65-70 Lap Shear Strength, PSI Open Molded FRP 580 755 715 955 820Failure Mode 100% FT 100% FT 100% FT 100% FT 100% FTIt is noteworthy that example 3, which contains a nitrile elastomer, didnot cure as effectively as the other examples in this series. This isbelieved to be the result of the antioxidant type and or level employedin the elastomer as supplied by the manufacturer. As noted in thespecification and the examples that follow, adjustments in the type orlevel of amine promoter, or in the level of BPO paste can be used toinfluence the curing behavior of individual compositions.

EXAMPLES 8-12

Examples 8-12 illustrate that alternative catalyst systems can be usedeffectively to take advantage of the modification of the curing behaviorof the inventive compositions. A preferred vinyl ester resin and apreferred DCPD resin are used to illustrate this effect in theseexamples.

TABLE 3 EXAMPLE 8 9 10 11 12 MMA Monomer 55.60 55.60 55.25 55.00 55.00Nipol DN 4555 10.00 10.00 10.00 7.50 7.50 Hypalon 30 — — — 5.00 5.00Lauryl 5.00 5.00 5.00 5.00 5.00 Methacrylate BTA 753 18.00 18.00 18.0016.00 16.00 MAA 1.00 1.00 1.00 1.00 1.00 HET 0.40 — — — — DMPT — 0.40 —— — CHP — — 0.50 0.50 0.50 p-Toluene — — 1.00 — — sulfonyl chloride DowDerakane 10.00 10.00 10.00 10.00 — VE Resin 411-350 Reichhold 44-006 — —— — 10.00 DCPD Resin 55% BPO Paste 1.80 1.80 — — — Reillcat ASY-2 — —1.00 1.00 1.00 RESULTS Peak Exotherm 39 Gram Mass Min. to peak 33.6 46.373.4 35.7 56.8 Temperature, ° F. 269 227 244 311 317 Thick Cast BeadCure Observations 8 in × 2 in × 1.5 in Qualitative Cure Rank (1 = Best,4 = Worst) Surface Boil None None None None None Surface Boil Rank 1 1 11 1 Hardness, Shore D 50-55 20 65-70 70-75 60-65 Center of Bead 60-70 2570-75 70-75 65-70 Lap Shear Strength, PSI Open Molded FRP 490 555 465455 610 Failure Mode 100% FT 100% FT 100% FT 100% FT 100% FTExamples 8 and 9 illustrate that with other variables constant, HET canbe more effective than DMT in combination with BPO in promoting fullcure of a specific composition as measured by hardness of the curedcomposition. Examples 10-12 illustrate that a preferred vinyl esterresin and a preferred DCPD resin can be used to very effectively andbeneficially modify the curing behavior of compositions that employ thechlorosulfonated polyethylene/sulfonyl chloride/DHP cure system. It iswell known to those skilled in the art that such cure systems are highlyreactive and are difficult to control with respect to boiling andgassing in other than very thin bonds or small masses.

EXAMPLES 13-17

Examples 13-17 illustrate the effects of four different and preferredmodifier resins on the curing properties of a specific andcompositionally constant methacrylate formulation compared with acomparative formulation that contains no modifier resin.

TABLE 4 EXAMPLE (Com- parative) 13 14 15 16 17 MMA Monomer 50.00 50.0050.00 50.00 50.00 Nipol DN 4555 7.50 7.50 7.50 12.00 12.00 Nova NAS 304.80 4.80 4.80 4.80 4.80 LMA 1.50 1.50 1.50 1.50 1.50 HET 0.39 0.39 0.390.39 0.39 1,4-NQ 0.003 0.003 0.003 0.003 0.003 MAA 0.75 0.75 0.75 0.750.75 DBP 1.00 1.00 1.00 1.00 1.00 BTA 753 20.38 20.38 20.38 20.38 20.38Fumed Silica 2.20 2.20 2.20 2.20 2.20 Paraffin Wax 0.50 0.50 0.50 0.500.50 Eastman 711-1530 — 10.00 — — — Flex Ortho Resin Eastman 126-0863 —— 10.00 — — Flex ISO Resin Reichhold 44-006 — — — 10.00 — DCPD Resin DowDerakane — — — — 10.00 VE Resin 411-350 55% BPO Paste 1.80 1.80 1.801.80 1.80 RESULTS Peak Exotherm 39 Gram Mass Min. to peak 45.2 46 46 24026 Temperature, ° F. 280 254 256 199 289 Thick Cast Bead CureObservations 8 in × 2 in × 1.5 in Qualitative Cure Rank (1 = Best, 4 =Worst) Surface Boil Yes None None None None Surface Boil Rank 3 1 1 1 1Hardness, Shore D porous 55-60 60-62 0-10 60-63 Surface only)Examples 14 and 15 illustrate that the preferred orthophthalic andisophthalic resins provide similar reactivity as measured by the time topeak exotherm and peak exotherm temperatures. Examples 16 and 17illustrate that, relative to the orthophthalic and isophthalic resins,the preferred DCPD resin imparts much lower reactivity and the preferredvinyl ester resin provides much higher reactivity as measured by time topeak exotherm and peak exotherm temperature. As noted in thespecification and in the other examples the reactivity of examples 16and 17 would be readily adjusted with appropriate changes in the amountor type of initiator and promoter.

EXAMPLES 18-19

Examples 18-19 demonstrate the formulation of an adhesive for bondingClass A fiberglass panels without read-through by incorporating aflexible polyester base resin in the composition.

In order to demonstrate the bonding of a metal bracket to a fiberglasspanel, a 1 inch by 4 inch by 0.062 inch aluminum strip was bonded to therough side a 4 inch by 4 inch by 0.125 inch fiberglass panel with aclass A show surface using a 20 grams mass of adhesive. Spacers wereused to shim the bond at a thickness of ⅜ inch. The adhesive was allowedto complete the cure cycle to peak exotherm followed by cooling toambient temperature, with the results as noted at the end of Table 5.

TABLE 5 EXAMPLE 18 19 MMA Monomer 57.00 64.60 Hycar 1300X33 2.00 2.00Tyrin 3615P 12.50 12.50 BTA 753 18.00 18.00 HET — 0.40 DMPT 0.50 —Methacrylic Acid 2.50 2.50 Flexible Orthophthalic 7.50 — Polyester BaseResin 55% BPO Paste 1.80 1.80 RESULTS Peak Exotherm 20 Gram Mass Time topeak, min. 20.3 16.8 Temperature, ° F. 251 282 Print-Through NonePrint-through visible observed on show surfaceThe comparative print through was observed by the casual visualtechnique that is traditionally used by those skilled in the art. Thebonded assembly is positioned with the show surface perpendicular to astrong light source such as a fluorescent light fixture, and viewed atan oblique, nearly parallel angle. Under such conditions, the presenceor absence of print through is readily apparent.

EXAMPLES 20-21

Examples 20 illustrates an improved formulation that provides anadhesive with long open time that does not boil in a thick bead, andprovides full cure without softness or tackiness or lingering odor fromunreacted monomer in a thin film. Example 20 is an inventive compositionthat contains a flexible polyester resin. Example 21 is a comparativeexample that utilizes vinyl toluene to provide extended open time. Theexamples illustrate that the inventive composition does not exhibitboiling when applied in a thick (1 inch) bead, yet cures to a hard statein a thin (0.10 inch) film. The comparative example (formulated for slowcure) does not exhibit boiling in a thick bead, but it does noteffectively cure in the thin film as illustrated by the finger hardnesstest. Importantly, the inventive example has significantly longer openworking time than the comparative example, yet cures fully with a lowerpeak exotherm temperature. When formulated for faster curing, theinventive example does not boil, but the comparative example does.

Comparison of examples 20B and 21B illustrates a significant improvementin the tensile strength and elongation of the inventive compositioncontaining the polyester resin.

TABLE 6 EXAMPLE 20 21 MMA Monomer 50.00 56.50 Lauryl Methacrylate 1.504.00 Nipol DN 4555 7.50 7.50 NAS-30 4.80 4.80 Paraloid BTA 753 20.4018.00 Flexible Orthophthalic 10.00 — Polyester Base Resin Vinyl Toluene— 1.25 Methacrylic Acid 0.75 1.75 Dibutyl Phthalate 1.00 2.30 HET 0.390.30 1,4-Naphthoquinone 0.003 — 5% EDTA Solution 1.00 1.00 Fumed Silica2.20 1.90 Paraffin Wax 0.50 0.70The results labeled 20A and 21A were obtained when formulations 20 and21 were mixed in ratio of 43:5 by weight with IPS Weld-On® SS 218 HVBactivator, a proprietary curative paste containing 5.6 percent benzoylperoxide by weight. Results 20B and 21B were obtained with anexperimental curing paste containing 7.7 percent benzoyl peroxide. Thecure state observations were made four hours after the achievement ofpeak exotherm.

RESULTS 20A 20B 21A 21B Cure behavior, 25 gram mass Open working time,min. 73.6 47.3 53.1 46.0 Peak exotherm time, min. 93.4 66.4 72.4 61.3Peak exotherm temp. ° F. 216 242 244 268 Thick bead cure results Beaddimensions 2 in × 6 in × 1.0 in thick Surface boil observed no no no yesHardness, Shore D 55 60 60 55 Monomer odor no no no no Thin film cureresults Film dimensions 2 in × 6 in × 0.10 in thick Surface boilobserved no no no no Hardness to touch hard hard soft hard Monomer odorno no yes no Tensile Properties ASTM D638 Stress at Failure (psi) 32712840 Elongation (%) 198 180

EXAMPLE 22

Example 22 illustrates the improvement in adhesive bond strength atelevated temperature obtained with the addition of a vinyl ester resin.Example 22B, which contains 10 percent of a preferred vinyl ester resin,has more than twice the bond strength at 250° F. than comparativeexample 22A which contains no additive resin. The fiber tearing bondfailure mode exhibited by Example 22B further illustrates the higherelevated temperature strength of the cured inventive adhesiveformulation.

ADHESIVES ACTIVATOR EXAMPLE 22A 22B 22C Tyrin 3615P 12.00 — — Hycar 1300X33 2.00 — — PARALOID BTA 753 17.50 — 12.00 MMA Monomer 58.80 — 55.75Methacrylic Acid 6.00 — — Paraffin Wax 0.65 — 1.25 Fumed Silica 0.75 — —Titanium Dioxide 22.00 MEKP 0.75 — — CHP 0.75 — — 2,4-Pentanedione 0.80— — 12% Cobalt Octoate — 3.00 DMPT — 6.00 1,4-Naphthoquinone 0.005 0.0050.01 Total 100.005 100.005 100.01 BLENDED ADHESIVES Grams of Adhesive100.00 90.00 VE 9420 Vinyl Ester 0 10.00 Resin Grams of Activator 10 10RESULTS Lap Shear Strength ASTM D5868 Bond Strength 125 270 at 250° F.,psi Failure Mode CF(100%) FT(50-100%)

EXAMPLE 23

Example 23 illustrates an inventive composition that is capable ofbonding fiberglass panels with no observable print-through as well asbonding aluminum with no surface preparation. Adhesion to unpreparedaluminum is achieved through the addition of a methacryloyloxyethylphoshpate ester.

EXAMPLE 23 Neoprene AD-10 12.5 Tyrin 3615P 9.0 Nipol DN 4555 4.0Flexible Orthophthalic 5.00 Polyester Base Resin Phosphate Ester 1.20Methacrylic Acid 5.00 HP1310 Acrylic Oligomer 3.80 DMPT 1.41,4-Naphthoquinone 0.0035 MMA Monomer 53.06 Paraloid BTA 753 5.00The adhesive was mixed at a ratio of 8.3 to 1 by weight with Weld-On SS605B activator, a proprietary paste containing 13.5 percent BPO byweight. Print through test was performed as in Example 18.

RESULTS Peak Exotherm 10 Gram Mass Open time, min. 5.1 Time to peak,min. 9.4 Temperature, ° F. 229 Print-Through None observed Lap ShearStrength, R.T. 2638 psi, 100% CF Aluminum, ASTM D1002 Lap ShearStrength, R.T.  899 psi, 100% FT Aluminum/FRP, ASTM 5868

Although the present invention has been described with reference to thepreferred embodiment, it will be appreciated that the description hasbeen made for the purpose of understanding the present invention, andvarious changes and modifications can be made without departing from thescope of the invention.

1. A polymerizable adhesive or filling composition comprising about 5 toabout 75 percent, by weight, of a blend of a) at least one crosslinkedor partially crosslinked polymer or elastomer, and b) at least onesoluble thermoplastic polymer or elastomer, about 0.5 to about 35percent, by weight, of a vinyl ester resin derived from the reactionproduct of a polyepoxide and an unsaturated monocarboxylic acid and thesubsequent addition of a styrene monomer, and about 20 to about 80percent of an alkyl acrylate or methacrylate monomer.
 2. Thepolymerizable adhesive or filling composition of claim 1 wherein thealkyl acrylate or methacrylate monomers comprise a C1-C6 acrylate ormethacrylate monomer selected from the group consisting of methylmethacrylate, ethyl methacrylate, hydroxyethyl methacrylate, propylmethacrylate, hydroxypropyl methacrylate, butyl methacrylate, hexylmethacrylate, cyclohexyl methacrylate, methyl acrylate, ethyl acrylatehydroxyethyl acrylate, propyl acrylate, hydroxypropyl acrylate, butylacrylate, hexyl acrylate, cyclohexyl methacrylate, or mixtures thereof.3. The polymerizable adhesive or filling composition of claim 1 furthercomprising from about 0.01 to about 20 percent by weight of apolymerizable organic acid monomer or oligomer.
 4. The polymerizableadhesive or filling composition of claim 3 wherein the polymerizableorganic acid monomer comprises methacrylic acid or acrylic acid ormixtures thereof.
 5. The polymerizable adhesive or filling compositionof claim 3 wherein the polymerizable organic acid monomer is selectedfrom the group consisting of maleic acid, fumaric acid, itaconic acidand mixtures thereof.
 6. The polymerizable adhesive or fillingcomposition of claim 3 wherein the polymerizable organic acid monomer oroligomer comprises a vinyl substituted phosphate ester.
 7. Thepolymerizable adhesive or filling composition of claim 1 furthercomprising from about 0.1 to about 10 percent by weight of a viscositycontrol agent.
 8. The polymerizable adhesive or filling composition ofclaim 1 further comprising one or more materials selected from the groupconsisting of catalysts, initiators, reducing agents, activators, andpromoters and mixtures thereof.
 9. The polymerizable adhesive or fillingcomposition of claim 1 further comprising an organic sulfonyl chlorideor a chlorosulfonated polymer and a dihydropyridine.
 10. Thepolymerizable adhesive or filling composition of claim 1 furthercomprising at least 0.5 percent, by weight, of a polyester resin. 11.The polymerizable adhesive or filling composition of claim 10 whereinthe polyester resin is selected from the group consisting oforthophthalic, isophthalic, terephthalic, halogenated polyester resinsand mixtures thereof.
 12. The polymerizable adhesive or fillingcomposition of claim 1 further comprising at least 0.5 percent, byweight, of a dicyclopentadiene resin.
 13. The polymerizable adhesive orfilling composition of claim 1 further comprising at least 0.5 percent,by weight, of an orthophthalic resin.
 14. The polymerizable adhesive orfilling composition of claim 1 wherein the crosslinked or partiallycrosslinked polymer comprises a core-shell impact modifier.
 15. Thepolymerizable adhesive or filling composition of claim 14 wherein thecore-shell impact modifier is selected from the group consisting ofmethacrylate butadiene styrene (MBS), acrylonitrile butadiene styrene(ABS), and an acrylic based or ethylene propylene core-shell impactmodifier.
 16. The polymerizable adhesive or filling composition of claim1 wherein the crosslinked or partially crosslinked polymer is selectedfrom the group consisting of a crosslinked polychloroprene elastomer, acrosslinked butadiene acrylonitrile elastomer, and a crosslinkedacrylate polymer or terpolymer and mixtures thereof.
 17. Thepolymerizable adhesive or filling composition of claim 1 wherein thesoluble thermoplastic polymer or elastomer comprises a diene basedpolymer comprising butadiene or isoprene, including liquid polymers andcopolymers of butadiene.
 18. The polymerizable adhesive or fillingcomposition of claim 17 wherein the diene based polymer or elastomercomprises a copolymer of butadiene, isoprene, or a combination ofbutadiene or isoprene with styrene, acrylonitrile or an acrylic monomer.19. The polymerizable adhesive or filling composition of claim 1 whereinthe soluble thermoplastic polymer or elastomer comprises a blockcopolymer of butadiene, isoprene, or mixtures of butadiene and isoprene,ethylene-propylene or ethylene-butylene with styrene.
 20. Thepolymerizable adhesive or filling composition of claim 1 wherein themonomer comprises a higher molecular weight monofunctional orpolyfunctional monomer.
 21. The polymerizable adhesive or fillingcomposition of claim 20 wherein the monomer comprises laurylmethacrylate.